Pipe bending machine



Dec. 26, 1961 J. D. CUMMINGS PIPE BENDING MACHINE 3 Sheets-Sheet 1 Filed Dec. 29, 1958 M 17. (umm/ngs INVENTOR.

BY 9 6 1w? ATTORNEY Dec. 26, 1961 J. D. CUMMINGS PIPE BENDING MACHINE 3 Sheets-Sheet 2 Filed Dec. 29, 1958 L/. 5. fumm/ngs INVENTOR.

ATTORNEY Dec. 26, 1961 J. D. CUMMINGS 3,014,518

PIPE BENDING MACHINE Filed Dec. 29, 1958 3 Sheets-Sheet 5 O O O 0 O O O 4/. D. Cum/77? J JNVENTOR.

BY QC? AMI? ATTOF/VEV tats dfiidfiiii Patented Dec. 26, 1961 3,014,518 PIPE BENDING MACHINE James D. Cummings, San Marcos, Tex., assignor to Crutchcr-Rolfs-Cummings, Inc., Houston, Tex., a corporation of Texas Filed Dec. 29, 1953, Ser. No. 783,459 4 laims. ((31. 153-44) This invention relates to machines for cold bending thin wall large diameter steel pipe such as currently is employed for the installation of oil and gas transmission lines. To reduce costs of material and handling of pipe, the trend is toward lighter weight and thinner pipe walls with adequate strength obtained through the use of selected steel content which has a degree of hardness much greater than pipe materials used in the past. The thinner and harder the wall, the more likely the cold bending will cause formation of compression wrinkles on the inside arc and an out-of-roundness or inward deflection with tension stretch of the pipe material on the outer arc of curvature. Lack of circularity and of smooth internal surfaces increase fluid flow resistance and interfere with travel of pigs and working bodies through the pipe line.

An objectrof the present invention is to provide an improved bending machine for more easily handling and working steel pipe to desiredcurvature and for the maintenance of circularity and smoothness at the wall region undergoing bending and resultant stretching and crowding stresses.

A further object of the invention is to provide an improved internal wall supporting and strain bucking jig which can be held in expanded bearing on the inside of a wall portion undergoing bending force and thereby minimize ovalarity from inward deflection under tension in the pipe wall along its outer arc of curvature and also the crowding and wrinkling from compression force in the pipe wall along the smaller arc of pipe curvature.

Another object of the invention is to provide an improved arrangement for properly locating the bucking jig against axial and rotational displacement internally of a pipe being bent during times of both a bending operation and a travel of the pipe through the machine in intervals between successive bending operations, together with powered traction drive mechanism for shifting the pipe and eliminating the cost and expense for at least one of the two boom carrying tractors usually employed with machines of this type for suspending oppositely projected end portions of the pipe and for shifting the pipe etween'bending operations.

Other objects and advantages will become apparent during the course of the following specification having reference to the accompanying drawings and wherein FIG. 1

isja' perspective view showing the rear end of a pipe bending machine embodying the improvements herein to be disclosed; FIG. 2 is a longitudinal vertical section of the machine showing a portion of the pipe positioned therein in preparation for the first stage of bending; FIG.

3 is a transverse section on line 3 -3 of FIG. 2 but on a larger scale; FIG. 4 is a fragmentary longitudinal vertical section with the operating parts similar to those of FIG. 2 as related to one another in a final stage of bending operation on a pipe; FIG. 5 is a side elevation with parts in vertical'longitudinal section of a portion of a bucking jig on enlarged scale; and FIG. 6 is a transverse section as on line 6-6 of FIG. 5. r

' For the bending of a pipe in a vertical plane and near the point of pipe line'installation, the machine as shown in the drawings involves an upper stationary die 1 and a lower movable die 2, both mounted in a structural steel framework comprising overheadbeams 3 supported by vertical side bars 4 from lower framing members 5. An operator station and the power drive and control the wheel.

equipment are suitably mounted on and above the frame superstructure. At the rear, the lower frame members 5 are supported by ground engaging wheels or tracks 6 and at the front by a skid assembly 7 which can be picked up for transportation by a suitable towing vehicle.

The upper die member 1 is fixedly mounted beneath the overhead structure 3 and has a downwardly facing and generally semicylindrical die cavity whose pipe wall working face is specially shaped in the upper region to recede progressively upwardly from back to front along a predetermined line of curvature on the radius to which the pipe is to be bent. The other die 2 is generally referred to as a stiff back and it contains an upwardly facing semicylindrical or troughlike die cavity whose radius substantially conforms to that of the pipe to be operated upon and is uniform throughout lower die or stiff back length, which usually is at least double the length of the fixed die 1. Rearwardly the dies are in vertical alignment and forward-1y the movable lower die projects considerably ahead of the upper die for adequate pipe support area.

The lower die is cable-suspended from the overhead structure? and for that purpose a set of cable pulleys is provided, including pulleys such as shown at 8 on both sides at the front and the rear of the die 2 for co-operation with similarly located pulleys, as shownat 9, mounted on the frame superstructure for harnessing a flexible cable to entrained on the several pulleys and joined to a power driven cable winding drum it. Through the cable suspension means the stiff back die 2 can be lowered to an open position, as shown in "EEG. 2, when the cable is paid out. When wound up on the drum 11, the suspension cable will raise the movable stiff back die 2, first to clamp between it and the fixed die the upper and lower faces of a pipe and then react with the fixed die to rock and press the pipe against and progressively bend the pipe along the curved under surface of the fixed die 1. Co-operating with the dies during the bending operation is a transversely pivoted pad 12 mounted on the frame base 5 rearwardly of the dies 1 and 2 and the pad provides a reaction bearing for and rocks to fit the surface of pipe beyond the pipe wall clamped by the bending dies 1 and 2. All the structure thus far described is'conventional and'well known.

According to the present invention, a section or joint of pipe 13 is introduced into the front end of the machine and between the open dies until its entering end extends beyond the dies and is rested on the rockable pad 12. Usually the bend in a pipe is formed throughout the intermediate portion of its length and bending is not performed in the portions of the pipe immediately adjacent its'opposite ends. In a forward portion of the lower die 2, the bottom wall of the die is recessed or cut through and provides an opening 14 through which projects a traction wheel 15 when the dies are open. This wheel 15 has a drive shaft mounted in trunnion bearings 1-6 on the lowerframe assembly 5 so that the wheel can be rotated on an axis transverse to the direction of pipe travel through the machine. The mounting presents the upper wheel tread at a slight elevation above the face of the open die cavity and the bottom of the pipe rests on Application of drive force to the wheel 15 in one direction or the other propels the pipe forwardly or backwardly through the machine. The mounting shaft for the traction wheel 15 can be geared through a drive 'chain to a jack shaft 17 which in turn can be geared to a hydraulic motor or through a drive train from the same power plant by which the cable drum ii. is driven.-

Fitted interiorly of the pipe 13 in the region thereof which undergoes bending stress during die operation, is an internal wall bucking jig comprised essentially of an assembly of radially expansible shoes lid arranged in opposing upper and lower sets. The shoes of each set are in close side by side relation, with small intervening clearances, as best seen in FIG. 5, to accommodate a degree of relative angular displacement of the shoes in relation one to another to fit bent curvature of the pipe illustrated in FIG. 4. To tie the shoes together and'accommodate the angular displacement referred to, each shoe has a radially inwardly extending stiffening rib 19 containing one or more perforations, each for alignment with similar perforations in adjoining webs and through which a long flexible steel rod 20 extends. In drawing, four such tie rods are shown for each set of shoes to insure axial alignment with one another and the outermost of the rod receiving perforations are formed in lugs or ring members 21 welded to the opposite terminals of the shoes 18. Tubular spacer sleeves 22 of elastic deformable material such as rubber surround each flexible rod 29 between adjoining shoes. These spacer sleeves tend to maintain longitudinal clearance between adjoining shoes but yield axially or deform to accommodate angular spacing variations during pipe bending operations. I The end plates 23 and 24 are fixedly tied together by being welded or otherwise joined to the opposite ends of a pair of transversely spaced flat straps 25 and 26 (see FIG. 6) of spring steel. Along their inner edges both straps 25 and 26 have a series of inwardly projecting short length fingers 2.7 welded thereto above and below the straps to form a guideway and support for a third flexible strap 28 which occupies the space between the straps 25 and 26 and is slidable longitudinally relative thereto.

Arranged above and below the intermediate spring steel strap 23 and welded thereto are a series of eyes 29 to receive pintle pins 39 to extend through mating eyes at the inner ends of shackle links 31 projecting above and below the fiat plates. At their outermost ends, terminal eyes of the shackle links 31 are joined by pivot pins 32 to spaced eyes 33 carried by the shoe stiffening webs 19. Relative longitudinal slide movement of the intermediate strap 28 is transmitted through the several shackle links 31 for radially expanding and contracting both sets of shoes 18 between the expanded full line positions and the contracted broken line positions shown in FIG. 6. The application of radial force through the expander links 31 and shoes 18 against the inside of the pipe 13 is thus in a direction at right angles to the planes of the straps 25, 26 and 28 and in the direction of relative die movement. When expanded, the internal shoes maintain pipe circularity and buck the inner wall against the formation of wrinkles under compression and tension stresses applied thereto. During a bending operation, the internal jig bends with the pipe, which is to say each expanded shoe remains in face to face bearing and moves with a part of the wall and movement of the shoes relative one to another is permitted by bending of the flexible tie rods 20 and straps 25, 26 and 28 in planes normal to the horizontal flat faces of the straps.

When the shoes are contracted away from the pipe wall, the assembly is supported directly on the inside of the pipe by a number of rollers which ride on the pipewall. Two of such rollers 34-34 are illustrated in FIG. 6 mounted on upwardly and outwardly inclined axes by means of brackets 35 depending downwardly from the supporting straps 25 and 26. In the regions of the rollers one or more of the adjoining shoes of the bottom set are cut away at opposite sides to afford roller clearance. Two longitudinally spaced sets of such supporting rollers 34 are preferably used, as is best seen in FIG. 2. In addition,

the forward end of the jig assembly carries a pipe engaging supporting wheel 36 for rolling contact on the pipe during the feed thereof in the machine. This front wheel 36 is bracketed on a piston housing or cylinder 37 mounted on a longitudinal axis and bolted at its rear end to the jig end plate 24. A similar piston cylinder 38 is bolted rigidly to and supported by the rear end plate 23 and a pair of pistons .39 are contained Within the cylinders and are rigidly joined to opposite ends of the sliding central strap 28 whereby pressure fluid under suitable control can be supplied to one end or the other of the pair of cylinders and move the pistons for the expansion or contraction of the expander shoes 18.

It is essential that the internal jig be maintained longitudinally aligned with the bending jigs and against rotation from a position in which shoe expansion occurs in the same direction as that of the relative movement of the bending dies and which is normal to the flat plane containing the flexible straps 25, 26 and 28, whose bending at right angles to the plane thereof accommodates angular variation between the several shoes in compensation for die action. Accordingly, the rearward end of the pressure cylinder 38 has connected thereto by a transverse hinge pin 4% the forward end of an elongate rod 41 which extends rearwardly from the machine for a distance greater than the length to which any pipe will extend rearwardly from the bending dies. This rod 41 preferably follows an arcuate curvature such that it can be readily received within the rearwardly extending bent portion of a pipe. At its rearward end it is connected by a transverse hinge pin 42 to a swingable boom or U-shaped frame 43 whose side legs are suitably braced and projected forwardly in outrigger relation from connections on a transverse axis to hinge brackets 44 at the rear of the machine supporting frame.

Adjustable chains, as shown at 45, connect the swingable boom 43 to an upright post 46 above the main frame at its rear end. Pipe or hose connections 47 extend from suitable valving at the operator's station above the machine along the swingable frame or boom 43 to its free end and then back along the curved locating rod 41 for controlling the supply of pressure fluid to the piston motor cylinders 37 and 38. The set position of the boom by means of the supporting chains 45 can be varied so that the longitudinally curved locating rod 41 can be used with any of a number of dies 1 of different curvature. For raising and lowering the outrigger boom assembly, its free end is joined to a cable 48 which runs over a pulley at the upper end of the post 46 to a winding drum 49 operated by a suitable motor or gear box 50 receiving power from the power plant of the machine and being under control of the machine operator. Optionally and either alone or supplemental to either the chain 45 and suspension cable 48, a piston and cylinder 51 suitably pivotally connected to the boom and the machine frame, can be employed for positioning the boom.

In the use of the equipment, the swingable boom and the locator rod 41 are set to project at a desired angle as accommodated by the pivot mountings 44 and the pivotal interconnections 40 and 42, all serving to anchor the internal jig against rotational and longitudinal displacement in relation to the bending dies. Before a pipe is inserted into the machine, the internal jig will be supported by its bottom wheels 34 and 36 on the upper surface of the lower die 12. With this lower die in its open position, the end of a pipe can be entered first into the forwardly extending portion of the trough of the lower die and rested on the traction wheel 15. Further inward movement of the pipe to position it for the first stage of bending can be effected in part by the traction wheel 15 and the usual pipe handling tractor ahead of the machine. When once the first bending stage is reached, the independent tractor can be freed of the pipe and the bending machine will handle the pipe from then on by itself. In intervals between successive bending operations, the stiff back or lower die 2 will be below the pipe resting on the traction wheel 15, whose controlled power drive will shift the pipe rearwardly to its next incremental pipe portion to be bent. In such successive advances of pipe travel the internal jig assembly will be supported by its rollers 36 and 34 on the inside of the pipe and will continue tobe located in proper die relation by the rearwardly extending outrigger structure. At the start of each die closing position, the internal shoes will be expanded and held in tight bucking relation with the pipe wall throughout the bending operation. At the end of each bending operation and before the pipeis driven rearwardly by' the traction wheel 15, the internal jig shoes will be contracted out of engagement with the pipe wall for support by their pipe engaging wheels or rollers. 7

From the above description it will be apparent that there has been provided an improved pipe bending machine wherein the parts are maintained properly related to one another for co-operation in preserving circularity and smoothness in a pipe Wall during the bending thereof and which is of special utility for handling large diameter pipe whose wall is relatively thin and relatively hard steel. While only a preferred embodiment of the invention has been described in. detail, it will be understood that various modifications can be made such as come within the scope of the appended claims.

What is claimed is:

1. In a machine for cold bending steel pipe, a supporting frame, a pair of relatively movable bending dies, means mounting said dies one above the other on the frame and accommodating relative vertical die movement between open die position and closed die position, a power driven traction wheel mounted on the frame to present its upper pipe engaging tread relative to the pipe engaging surface of the lowermost die above the latter in open die position and below the same in closed die position, an'internal pipe fitting jig having an axial succession of radially adjustable shoes, shoe expander links connected at their outer ends to the shoes, an axially projected strap extended through the shoe assembly and connected with the inner ends of said links, another strap having guide and sliding engagement with the first mentioned strap, means interconnecting said radially adjustable shoes and the second mentioned strap against relative displacement axially and rotationally while accommodating radial shoe adjustment, a supporting wheel connected to one end of the second mentioned strap and adapted to roll on the interior of a pipe when the latter is shifted by said traction wheel, a piston cylinder connected with the other end of the second mentioned strap,

an elongate rod connected at one end with said piston cylinder and projected to its opposite end a distance to extend through and beyond the end of a surrounding pipe on which successive bending operations have been completed, an outrigger support connected with said opposite end of the rod and mounted on said frame to thereby locate said second mentioned strap and the jig shoes interconnected therewith against displacement axially and rotationally within the pipe to be bent and to hold said straps in planes transverse to the direction of relative bending die movement and accommodate strap flexing and relative shoe movement during a pipe bending operation, a power actuated piston within said piston cylinder and an operative connection joining said piston to the first mentionedstrap to elfect actuation of the first mentioned strap for the transmission of expansion and contraction force to move the strap interconnected shoes to and from bucking relation with the interior wall surface of the pipe portion sleeved thereon.

2. In a pipe bending machine, a main frame, relatively movable exterior bending dies mounted by the main frame and operative to clamp against the outside of diametrically opposed wall portions of a selected length increment of pipe and to bend the same on a longitudinal line of curvature, an internal expanding shoe assembly for bucking engagement with said diametrically opposite wall portions on the inside thereof, means locating the internal shoe assembly against displacement from cooperative longitudinal and circular alignment with the exterior dies including an elongate rod longitudinally curved in substantial conformity to pipe bending curvature and secured to the shoe assembly and projected rearwardly therefrom a distance to extend through and beyond the rearward end of a pipe clamped between the dies and a boom carried by and projected in outrigger relation to the main frame and secured to the rearward end of said elongate rod, a traction wheel mounted on the main frame in position for pipe engagement when the dies are at their open limit of relative movement and the pipe wall while the same is being bent, an elongate rigid locating rod pivotally secured to the jig and projected outwardly therefrom on a fixed line longitudinally curved in conformity to the curvature of bent pipe for telescopic reception of bent pipe fed in steps successively through the machine, means connected to the outwardly projected portion of the longitudinally curved locating rod and resistant to movement thereof both longitudinally and rotationally of its projected extent and comprised of a boom pivotally mounted .at one end on the machine and joined at its other end to the outwardly projected portion of said locating rod and an adjustable support positioning said boom is selected swing settings about its pivotally mounted end and thereby setting the projection angle of the jig locating rod about said pivotal connection to suit the curvature of bent pipe surrounding the rod. 7

4. In an internal jig assembly for bucking the thin wall of large diameter steel pipe during cold bending thereof, a supporting frame having a pair of transversely spaced and coplanar flat flexible steel straps and opposite end header plates secured to both straps, two sets of longitudinally successive pipe engaging bearing shoes arranged between said end header plates and on opposite sides of the fiat flexible steel straps for movement toward and from pipe engaging position in a direction normal to the plane of said straps and to follow bending curvature of pipe engaged by the shoes, flexible tie means interconnecting the shoes of each set with both end header plates of the supporting frame, expander links connected to and extended inwardly from each shoe, a centrally disposed and longitudinally slidable flat' flexible steel strap connected to said links, means slidably mounting the last mentioned strap on and in a plane parallel to the plane of the first mentioned flat straps and longitudinal force applying means joined to said slidable flat strap.

References Cited in the file of this patent UNITED STATES PATENTS 174,608 Wright Mar. 7, 1876 1,105,914 Miller Aug. 4, 1914 1,389,856 Brinkman Sept. 6, 1921 1,890,039 Lange Dec. 6, 1932 2,347,593 Cummings Apr. 25, 1944 2,401,052 Cummings May 28, 1946 2,453,531 Myers Nov. 9, 1948 2,615,413 Adams et al Oct. 28, 1952 2,708,471 Ballard May 17, 1955 FOREIGN PATENTS 17,807 Great Britain 1895 610,607 Great Britain Oct. 19, 1948 50,028 Netherlands Mar. 15, 1951 

